Mathematical instrument.



A. GARINGER.

MATHEMATICAL INSTRUMENT.

APPLICATION TILED JULY 28, 1911.

Patented Nov. 7, 1911.

COLUMBIA PLANOGRAPH co.,wASHINGTON. 11.5.

ALBERT GARINGER, OF STAMFORD, CONNECTICUT.

MATHEMATICAL INSTRUMENT.

Original application filed April 1, 1911, Serial No. 618,381.

Specification of Letters Patent.

Patented Nov. '7, 1911.

Divided and this application filed July 28, 1911.

Serial No. 641,045.

T 0 all whom it may concern:

Be it known that I, ALBERT GARINGER, a citizen of the United States, anda resident of the city of Stamford, in the State of Connecticut, haveinvented certain new and useful Improvements in MathematicalInstruments, of which the following is a specification.

My invention relates to devices for drawing curves, and particularlycurves of the type known as conchoid curves.

In the accompanying drawings, Figure 1 is a plan view of an instrumentconstructed according to my invention; Fig. 2 is a vertical section ofthe same, taken on the line 2-2 of Fig. l; and Figs. 3 and 4 are detailviews, being vertical sections taken on the lines 33 and 44 of Fig. 1respectively.

The invention herein described and shown in the accompanying drawings,is a modification of an invention described and shown in an accompanyingapplication made by me and filed in the United States Patent Office onApril 1, 1911, bearing the Serial No. 618,381, this application being adivision of the said accompanying application. In carrying this form ofmy invention into effect I provide three members of suitable size,designated respectively 10, 11 and 14. The members 10 and 11 arepivotally connected together by a set-screw 15, the same, and the mannerin which it connects the said members being shown more in detail in thesectional view Fig. 3. This construction is such that by tightening theset screw 15 the members 10 and 11 may be firmly set or fixed at anydetermined angular relation to each other. The member 10 is formed intosuch a shape that one of its edges-the upper edge in Fig. 1-constitutesan extension of the center line of the pivot 15, and this upper edgecorresponds to the directrix of the conchoid curve to be traced. Themembers 11 and 14 are pivotally connected to gether by the pivot 17, sothat the member 14 is always free to swing angularly with relation tothe member 11. This pivot 17 corresponds to the focus of the curve. Themember 14 is provided for approximately the outer half of its lengthwith a slot having walls which slope downward and in ward, and in thisslot slides an extension arm 12, the sides of which slope in acorresponding manner so as to engage with the sloping walls of the slot.This construction is best shown in the transverse section Fig. 4. Theinner end of the extension or sliding member 12 is provided with adownwardly projecting heel 18, the inner end of which is wedge shapedand provided with a knife-edge, as shown at 16 in Fig. 1. Thisknife-edge 16 bears against the directrixedge of the arm 10. The outerend of the extension or sliding member 12 is provided with a perforation18 into which may be inserted a pencil or other tracing point for thepurpose of placing upon paper the conchoid curve to be drawn.

The operation of my invention is as follows: The member 11 having beenfirmly fixed in any desired relation to the member 10 by means of theset-screw 15, a pencil or tracing point is placed in the perforation 18of the sliding or extension member 12. The said extension member 12 andthe member 14 are then swung around upon the pivot 17, the knife-edgeextremity of said member 12 being always kept in contact with thedirectrix-edge of the member 10. Upon performing this operation thetracing point carried by the free end of the member 12 will trace aconchoid curve, of which the pivot 17 represents the focus, and theupper edge of the member 10, with which the knife-edge 16 is in contact,represents the directrix.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is as follows:

1. An instrument for tracing conchoid curves, comprising a stationarymember an edge of which corresponds to the directrix of the curve, amember pivotally connected to said first named member and adapted to befirmly set at a determined angle with regard to said first named member,and a swinging member pivotally connected to said second member at apoint corresponding to the focus of the curve and provided with anextension member the inner end of which bears against the directrix edgeof the first member.

2. An instrument for tracing conchoid curves, comprising a stationarymember an edge of which corresponds to the directrix of the curve, amember pivotally connected to said first named member and adapted to befirmly set at a determined angle with regard to said first named member,and a swinging member pivotally connected to said second member at apoint corresponding to the focus of the curve and provided my hand inthe presence of two Witnesses, 10 with an extension member the inner endof h this 22d day of July, 1911.

whic is provided with a narrowed or wedgeshaped extremity which bearsagainst the ALBERT GARINGER' direotriX edge of the first named memberWVitnesses:

and the outer end of which is adapted to LILIAN M. WARNER, bear tracingor drawing means. HENRY SILVERMAN.

In witness whereof, I have hereunto set Copies of this patent may beobtained for five cents each, by addressing the "Commissioner ofIPatents, Washington, D. G.

